1. Field of the Invention
The present invention relates to a heat-sensitive switch used for an electronic circuit, etc., and a method for assembling the heat-sensitive switch. More particularly, the present invention relates to the heat-sensitive switch for which welding of a junction spring on a base is no longer required, whereby the manufacturing and assembling can be facilitated.
2. Description of the Related Art
There is an example of a conventional heat-sensitive switch used for an electronic circuit, of which structure is as per illustrated in FIG. 18. FIG. 18(a) is a plan view showing an overall structure of the heat-sensitive switch, and FIG. 18(b) is a sectional view as seen by the line b-b of FIG. 18(a).
There is a chassis 201, in a shape of container having a bottom surface, comprising a bottom panel 203 and side walls 205. The chassis 201 has an upper opening part 207, which has been closed by a cover 209.
For the purpose of clarifying the inner structure, FIG. 18(a) does not illustrate the cover 209.
There are terminals 211, 213, respectively inserted and positioned on the left and right, inside the chassis 201.
There is a junction spring 215, incorporated and placed inside the chassis 201. An end of the junction spring 215 (the left end of FIG. 18) has been secured to a protrusive part 217 protruding from the bottom panel 203 of the chassis 201, and welded and fixed thereon in that state. Another end of the junction spring 215 (the right end of FIG. 18) has a junction part 219 provided on the lower surface.
There is also a reverse spring 221 under the junction spring 215, incorporated and placed inside the chassis 201. The reverse spring 221 comprises a so-called “bimetal” material.
According to the above structure, the heat-sensitive switch in normal state is as per shown in FIG. 18(b), wherein the junction part 219 of the junction spring 215 is in contact with the terminal 213. The other end of the junction spring 215 is also in contact with the terminal 211. Thus, the terminal 211 and the terminal 213 are electrically connected to each other.
Further, when the environmental temperature reaches a set temperature, which has been set in advance, the reverse spring 221 is reversed, and becomes in a form as shown by imaginary lines of FIG. 18(b), whereby the junction spring 215 is pressed upwardly. Consequently, the junction part 219 of the junction spring 215 moves away from the terminal 213, and the electric connection between the terminal 211 and the terminal 213 is cut.
On the other hand, when the once risen temperature goes down again, the reverse spring 221 returns to the original form, whereby the electric connection between the terminal 211 and the terminal 213 is resumed again.
Although having no direction relation, there is an analogous disclosure to the heat-sensitive switch of the present invention, such as in the Official Gazette of Japanese Unexamined Patent Publication No. Hei 10-21805.
However, the conventional heat-sensitive switch has a disadvantageous point.
According to the conventional structure, an end of the junction spring 215 should be welded and fixed on the side of the bottom panel 203 of the chassis 201, which requires a laborious assembling. In particular, the welding must be done after inserting the reverse spring 221 under the junction spring 215, which would cause poor working efficiency.